With the long term objective of understanding the interactions between Candida albicans and its human host this proposal examines the structural and functional dynamics of the Candidal cell surface. The microbial cell surface as the interface between the microbe and its environment is responsible for mediating host/parasite interactions and pathogenesis. The cell surface of C. albicans is dynamic, exhibiting changes in morphology, adherence and other properties relevant to the pathogenic process. These changes occur in response to culture conditions and exemplify adaptive responses that likely occur in vivo. The molecular basis of cell surface dynamics is as yet poorly defined. Molecular genetics provides a means of defining the molecular basis of cell surface structure and dynamics and this application focuses on the analysis of genes encoding cell surface proteins which are differentially expressed in response to environmental conditions. Because the dynamic changes in the cell surface result in altered properties relevant to the host/parasite interaction and because these changes occur in response to culture conditions, it follows that the differentially expressed genes encode biochemical or structural functions that are directly involved in establishing cell surface characteristics integral to the pathogenic process. Analysis of the structure and function of these genes will provide information essential to our understanding of C. albicans and its interaction with the host.